Idiopathic generalized epilepsies (IGEs) constitute one third of all epilepsies. They are genetically determined and affect otherwise normal people of both sexes and all races. IGEs manifest with typical absences, myoclonic jerks, and generalized tonic-clonic seizures, alone or in varying combinations and severity. Absence status epilepticus (ASE) is common. Most syndromes of IGE start in childhood or adolescence, but some have an adult onset. They are usually lifelong, although a few are age-related. The EEG is the most sensitive test in the diagnosis and confirmation of IGE. EEG shows generalized discharges of spikes, polyspikes, or spike/polyspike-waves either ictally or inter-ictally. These discharges are often precipitated by hyperventilation, sleep deprivation, and intermittent photic stimulation (IPS). Inconspicuous clinical manifestations become apparent on video-EEG and with breath counting during hyperventilation. The EEG is unlikely to be normal in untreated patients. In suspected cases with a normal routine awake EEG, an EEG during sleep and awakening should be obtained. Molecular genetic analyses have led to important breakthroughs in the identification of candidate genes and loci; genetic heterogeneity is common.

Treatment of IGEs is demanding for 2 main reasons. Firstly, some AEDs beneficial in focal epilepsies are contraindicated in IGEs. Secondly, efficacy of AEDs differs even within IGE seizures. Most IGEs respond well to appropriate AEDs, but treatment is often lifelong.

IGEs recognized by the International League Against Epilepsy (ILAE) are:

Childhood absence epilepsy

Epilepsy with myoclonic absences

Epilepsy with myoclonic-astatic seizures

Epilepsy with GTCS only

IGE with phantom absences

Juvenile absence epilepsy

Juvenile myoclonic epilepsy

Myoclonic epilepsy in infancy

Perioral myoclonia with absences

The epileptic syndromes and their significance

A major advance in recent epileptology is the recognition of epileptic syndromes that allows an accurate diagnosis and management of seizure disorders.[1-3]

Medical diagnosis is the identification of a disease by investigation of its symptoms and history, which provides a solid basis for the treatment and prognosis of the individual patient. An accurate diagnosis is the golden rule in medicine, and epilepsies should not be an exception to this. Like in any other disease, the recognition of non-fortuitous clustering of symptoms and signs in epilepsies requires the study of detailed clinical and laboratory data.[1-3] However, often in current practice, the diagnosis is limited to either epilepsy or seizures, which is unsatisfactory because this cannot provide guidance on important items such as severity of the disease, prognosis, short- and long-term therapeutic decisions, and genetics (research and counselling), which are all factors that crucially affect personal, family, and social life; education; and career choices of patients. Defining the type of epilepsy should now be considered mandatory as it offers the best guide to both management and prognosis. Most epileptic syndromes and diseases are well defined and easy to diagnose. The benefits of syndromic diagnosis over seizure/symptom diagnosis or an inclusive diagnosis such as epilepsy far outweigh any morbidity from incorrect categorization that may arise in difficult cases.[4]

Important clinical features of a syndrome include the type of seizures, their localization, frequency, sequence of events, circadian distribution, precipitating factors, age at onset, mode of inheritance, physical or mental symptoms and signs, prognosis, and response to treatment.

Epilepsies or epilepsy?

The clinical and practical significance of the syndromic diagnosis of epilepsies is well illustrated by 3 common epileptic disorders. Benign childhood focal epilepsies, juvenile myoclonic epilepsy (JME), and hippocampal epilepsy have nothing in common other than the fact that they may all be complicated by generalized tonic clonic seizures (GTCS), which are primarily GTCS in JME and secondarily GTCS in benign childhood focal epilepsies and hippocampal epilepsy.

Furthermore, the short-and long-term treatment strategies are entirely different for each disorder: benign childhood focal epilepsies may or may not require medication for a few years, appropriate anti-epileptic drug (AED) treatment is lifelong in JME while neurosurgery may be life-saving for patients with hippocampal epilepsy. What may be a life-saving drug such as carbamazepine for hippocampal epilepsy may be ill-advised for JME.

It should not be difficult to distinguish an intelligent child with benign focal seizures or childhood absence epilepsy from a child with Kozhevnikov-Rasmussen, Lennox-Gastaut, Down, or Sturge-Weber syndrome or a child with severe post-traumatic cerebral damage, brain anoxia, or catastrophic progressive myoclonic epilepsy. Describing all these children as simply having epilepsy just because they have seizures offers no more benefit than a diagnosis of febrile illness irrespective of cause, which may be a mild viral illness, a life-threatening acute bacterial meningitis, or a malignancy. Inappropriate generalizations with regard to terminology, diagnosis, and treatment are the single most important factor of mismanagement in epilepsies.[4]

C. P. Panayiotopoulos, MD, PhD, FRCP

Engel J Jr. A proposed diagnostic scheme for people with epileptic seizures and with epilepsy: Report of the ILAE Task Force on Classification and Terminology. Epilepsia 2001;42:796-803.

Commission on Classification and Terminology of the International League Against Epilepsy. Proposal for revised classification of epilepsies and epileptic syndromes. Epilepsia 1989;30:389-99.